1. Field of the Invention
The invention relates to a Marx generator and to use of a high-voltage cable for its high-voltage decoupling on the charging side.
The impulse-voltage generator discovered by Professor Marx (Braunschweig TU) in 1923 is used to produce a high-voltage pulse, for example for insulation-testing purposes, to investigate the behavior of gases in strong electrical fields or, according to DE 101 51 565 A1, to stimulate a resonator to emit high-power microwave energy.
The basic function of the Marx generator is based on a number n (n=1, 2, 3, . . . , i) of capacitors connected in parallel with one another being charged to an input voltage produced by a DC voltage source, and then being connected in series so that n-times the input voltage is available as the output voltage across this series circuit. In this case, the change from parallel connection to series connection of the capacitor bank is carried out by means of spark gaps which all ignite virtually at the same time when a first of them responds. The response of a first spark gap can be predetermined by means of its response voltage, that is to say by means of the cross-section geometry and the distance between the spark-gap electrodes; alternatively, the response of a first of the spark gaps is initiated by a trigger pulse supplied to it externally. Decoupling resistors, which also act as charging resistors that govern the time constants, prevent one of the two capacitors, between which a spark gap in order to connect them in series is located, being short-circuited as a result of the ignition of the spark gap. In consequence, the series connection of the charging and decoupling resistors when the capacitor bank is changed to be connected in series acts as a high-voltage voltage divider; and then both the input-side voltage source of the Marx generator and its output-side output line are connected to a high-voltage potential with respect to the common ground potential.
2. Discussion of the Prior Art
A commercially available electronic voltage converter is normally used as the voltage source for the Marx generator, is fed from a power supply system or from a chargeable battery, and charges the parallel circuit formed by the capacitor bank to a voltage of typically several 10 kV. The high-voltage reaction on the electronic system or from a chargeable battery, and charges the parallel circuit formed by the capacitor bank to a voltage of typically several 10 kV. The high-voltage reaction on the electronic circuit of this input-side voltage source on switching the capacitor bank from being parallel connected to being series connected is then functionally critical. This can lead to an adverse affect on the operation of the voltage source, or even to its destruction, so that stable long-term operation of the Marx generator, for example for continuous excitation of a microwave resonator, is not possible. Because of the high voltage load, conventional filter methods cannot be used in this case between the voltage source and the capacitor bank of the Marx generator, and the use of special high-voltage resistors for decoupling would be too costly.